Commit 9700b0fc authored by Bartosz Golaszewski's avatar Bartosz Golaszewski
Browse files

gpiolib: allow multiple lookup tables per consumer 

The GPIO machine lookup mechanism dates back to old ARM board files
where lookup tables would all be defined in a single place. Since then,
lookup tables have also been used to address various DT and ACPI quirks
like missing GPIOs and - as of recently - setting up shared GPIO proxy
devices.

The lookup itself stops when we find the first matching table for a
consumer and - if it doesn't contain the right entry - the lookup fails.

Since the tables can now be defined in multiple places and we can't know
how many there are, effectively limiting a consumer to only a single
lookup table is no longer viable.

Rework the code to always look through all tables matching the consumer.

Link: https://lore.kernel.org/r/20251222-gpio-shared-reset-gpio-proxy-v1-1-8d4bba7d8c14@oss.qualcomm.com


Signed-off-by: default avatarBartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
parent a05543d6

drivers/gpio/gpiolib.c

+56 −35
Original line number Diff line number Diff line
@@ -4508,45 +4508,41 @@ void gpiod_remove_hogs(struct gpiod_hog *hogs) 
}

EXPORT_SYMBOL_GPL(gpiod_remove_hogs);



static struct gpiod_lookup_table *gpiod_find_lookup_table(struct device *dev)

static bool gpiod_match_lookup_table(struct device *dev,

				     const struct gpiod_lookup_table *table)

{

	const char *dev_id = dev ? dev_name(dev) : NULL;

	struct gpiod_lookup_table *table;



	list_for_each_entry(table, &gpio_lookup_list, list) {

	lockdep_assert_held(&gpio_lookup_lock);



	if (table->dev_id && dev_id) {

		/*

		 * Valid strings on both ends, must be identical to have

		 * a match

		 */

		if (!strcmp(table->dev_id, dev_id))

				return table;

			return true;

	} else {

		/*

		 * One of the pointers is NULL, so both must be to have

		 * a match

		 */

		if (dev_id == table->dev_id)

				return table;

		}

			return true;

	}



	return NULL;

	return false;

}



static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id,

				    unsigned int idx, unsigned long *flags)

static struct gpio_desc *gpio_desc_table_match(struct device *dev, const char *con_id,

					       unsigned int idx, unsigned long *flags,

					       struct gpiod_lookup_table *table)

{

	struct gpio_desc *desc = ERR_PTR(-ENOENT);

	struct gpiod_lookup_table *table;

	struct gpio_desc *desc;

	struct gpiod_lookup *p;

	struct gpio_chip *gc;



	guard(mutex)(&gpio_lookup_lock);



	table = gpiod_find_lookup_table(dev);

	if (!table)

		return desc;

	lockdep_assert_held(&gpio_lookup_lock);



	for (p = &table->table[0]; p->key; p++) {

		/* idx must always match exactly */
@@ -4600,6 +4596,29 @@ static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id, 
		return desc;

	}



	return NULL;

}



static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id,

				    unsigned int idx, unsigned long *flags)

{

	struct gpio_desc *desc = ERR_PTR(-ENOENT);

	struct gpiod_lookup_table *table;



	guard(mutex)(&gpio_lookup_lock);



	list_for_each_entry(table, &gpio_lookup_list, list) {

		if (!gpiod_match_lookup_table(dev, table))

			continue;



		desc = gpio_desc_table_match(dev, con_id, idx, flags, table);

		if (!desc)

			continue;



		/* On IS_ERR() or match. */

		return desc;

	}



	return desc;

}
@@ -4610,16 +4629,18 @@ static int platform_gpio_count(struct device *dev, const char *con_id) 
	unsigned int count = 0;



	scoped_guard(mutex, &gpio_lookup_lock) {

		table = gpiod_find_lookup_table(dev);

		if (!table)

			return -ENOENT;

		list_for_each_entry(table, &gpio_lookup_list, list) {

			if (!gpiod_match_lookup_table(dev, table))

				continue;



			for (p = &table->table[0]; p->key; p++) {

			if ((con_id && p->con_id && !strcmp(con_id, p->con_id)) ||

				if ((con_id && p->con_id &&

				    !strcmp(con_id, p->con_id)) ||

				    (!con_id && !p->con_id))

					count++;

			}

		}

	}



	if (!count)

		return -ENOENT;